With increased levels of integration and increasingly smaller feature sizes, it is important that film deposition operations produce materials that adhere to all desired surfaces. This can be difficult to do if there is a surface tension mismatch between the film being deposited and at least some of the exposed surfaces upon which the material is being deposited. This creates a problem whereby the deposited material adheres well to some surfaces but delaminates from others.
Semiconductor devices are being manufactured to include stressor films to improve hole mobility in structures such as source/drain regions associated with MOSFET (metal oxide semiconductor field effect transistor) devices. Stressor materials are often materials with lattices that include large atoms and are formed by various thin film deposition methods. For example, SiGe materials may serve as stressor films and may be used to replace silicon and serve as source/drain structures for MOSFET's and other transistors in highly advanced semiconductor technologies. This improves device performance due to the increased hole mobility.
Source/drain structures are formed adjacent transistor gates that are disposed on a semiconductor substrate surface. When materials such as stressor materials are used for the source/drain regions, openings are formed in the semiconductor substrate adjacent the transistor gates. The desired materials must then be introduced into the openings using various deposition methods.
Another artifact of the high levels of integration is the presence of shallow trench isolation (“STI”) devices formed in the substrate in close proximity to the transistors. STI devices isolate active devices from other active devices. When the openings formed in a substrate are partially bounded by STI structures, the openings thus have different types of surfaces upon which the deposited material must adhere.
STI structures can exhibit surface tension characteristics that are different than the other surfaces of the opening in which the material is formed. One shortcoming associated with current methods and structures is the difficulty in overcoming the surface tension mismatch between the deposited material and at least one of the surfaces that border the opening.
The present disclosure addresses the shortcomings and addresses other needs in semiconductor manufacturing.